The present disclosure generally relates to a mixing device for combining and mixing liquids or gases. More specifically, the present disclosure relates to a steam injection heater in which a supply of heated steam flows inward into a slurry or liquid to be heated, where the flow path for the liquid to be heated does not include any flow obstructions.
In direct contact steam injection heaters, steam is directly mixed with a liquid or slurry product to heat the liquid or slurry product. Direct contact steam injection heaters are effective at transferring heat from steam to the liquid or slurry material. Steam injection heaters provide rapid heat transfer with virtually no heat loss to the atmosphere, and also transfer both the latent and available sensible heat of the steam to the material.
In several types of commercially available direct contact steam injection heaters, the flow of material travels in an axial direction and steam flows radially outward from a diffuser into the flow of liquid. In these types of direct contact steam injection heaters, such as shown in U.S. Pat. No. 6,082,712, the flow of slurry travels over an arduous path prior to the injection of steam. While this type of steam injection heater works well with various types of liquids and slurries having a relatively low solid composition, the heater has several drawbacks when heating slurries having a relatively high solid composition. When used with these types of slurries, the solid composition of a slurry often clogs the heater at the point in the heater in which the slurry changes directions.
In addition to the drawback set forth above, presently available direct contact steam injection heaters also create inconsistent heat transfer across the profile of the heater. The currently available direct contact steam injection heaters also have poor condensing characteristics, which can lead to instability and noise within the injection heater. Further, when the currently available direct contact steam injection heaters are utilized with delicate slurries, such as food, any obstructions in the flow path of the material being heated can change the physical properties of the product.
Therefore, a need and desire exists for an improved steam injection heater that can be utilized with slurries having relatively large solid components.